Conventionally, as a machine element part for moving a linear movement portion of a machine lightly and accurately, a rolling device such as a linear guide and a ball screw device is known. For example, the rolling device, as the linear guide includes a track rail and a movable block attached to the track rail to be movable in a reciprocating manner via balls installed as multiple rolling elements. The track rail is an elongated member with a cross-section thereof perpendicular to a longitudinal direction thereof formed approximately in a rectangular shape. On surfaces (an upper surface and both side surfaces) of the track rail, rolling element rolling grooves serving as tracks when balls roll are formed over the entire length of the track rail. Meanwhile, the track rail is formed to extend linearly or in a curved manner.
On the other hand, the movable block includes a movable block main body portion made of a metal material and a pair of end plates installed on tooth end surfaces of the movable block main body portion in a moving direction and made of a resin material. The movable block main body portion is provided with loaded rolling element rolling grooves at corresponding positions to the rolling element rolling grooves. Each rolling element rolling groove of the track rail and each loaded rolling element rolling groove formed in the movable block main body portion form a loaded rolling element rolling raceway. The plurality of balls guided into this raceway roll while being loaded. The movable block main body portion also includes non-loaded rolling element rolling raceways extending parallel to the loaded rolling element rolling grooves. Also, each of the paired end plates is provided with a direction changing raceway connecting each non-loaded rolling element rolling raceway to each loaded rolling element rolling raceway. Combination of one loaded rolling element rolling raceway and one non-loaded rolling element rolling raceway and a pair of direction changing raceways connecting them constitutes one endless circulation raceway.
By installing the plurality of balls into the endless circulation raceway constituted by the non-loaded rolling element rolling raceway, the loaded rolling element rolling raceway, and the pair of direction changing raceways to enable endless circulation, relative reciprocating movement of the movable block to the track rail can toe performed.